The present invention relates to method, apparatus and system for determining, in-process, the integrity of sealed containers. The invention has particular application to parenteral pharmaceutical products which are typically packaged in rigid glass containers sealed with a combination rubber and metal closure.
Such pharmaceutical products are usually packaged by high speed automatic filling and capping equipment. The containers or bottles are filled with the medicament at a filling station and thereafter the closure assembly consisting generally of a resilient sealing element made of rubber and a cup-like cap made of aluminum is placed over the discharge end of the container. The capping apparatus then acts to apply a predetermined force to the cap to seat the closure assembly and to crimp the lower edge of the skirt of the cap under or around the bottle finish or flange to seal the container. More specifically during the capping operation the resilient sealing element is compressed between the end face of the container and the cap and held in a compressed state by crimping the cap to the container. The integrity and adequacy of the seal is a function of the percent compression of the sealing element or expressed another way, the magnitude of the sealing force of the seal against the container around the periphery of the opening in the container. Proper sealing for medicaments is important to prevent exposure to air or loss by evaporation and also to protect the contents from microbiological or other contamination.
It has been found that some containers packaged by mass production techniques are not adequately sealed. The seal is controlled primarily by the capping equipment. For example, for a given cap, resilient sealing element and container assembly, the bottle-raising or cap lowering means of the sealing apparatus is initially set to apply a predetermined force to effect a given compression of the resilient sealing element to produce the proper seal. If the initial setting of the sealing apparatus is incorrect, the seal produced is inadequate. For example, if the preload force in the bottle-raising or cap lowering means is too low, the resilient sealing element is not compressed sufficiently to seal and if too high there is the danger of metal cap distortion, dimpling of the top surface of the resilient sealing element or glass breakage. Even if the initial setting of the sealing apparatus is correct, the setting may require adjustment by the operator from time to time and if these changes are inadvertently overlooked, inadequate sealing may result.
Presently there are various apparatus and systems for in-process determination of seal integrity of various types of containers which perform generally the functions of sensing, analyzing and removing defective sealing means.
For instance, in a system for checking seal integrity which is the subject of U.S. Pat. No. 3,206,025 means are provided for detecting the post-seal evacuated height of flexible container-closure assembly. The flexible cover is adapted to flex from a normal position to a downwardly generally concave position indicating a properly sealed package. An improperly sealed container would be one in which the cover is in a generally upwardly protruding convex position indicating the vacuum seal has been broken. The sealed packages are moved below a microswitch which comprises a top "feeler finger" or detecting arm adapted to overlie the cover so that it will sense whether the cover portion is up or down. Also provided by this patent is a memory storage circuit which in conjunction with the microswitch will act to reject an improperly evacuated container.
In another system for checking seal integrity which is the subject of U.S. Pat. No. 4,213,329 Raymond et al, METHOD AND APPARATUS FOR INSPECTING CONTAINERS a method and apparatus are provided for inspecting vacuum-packed containers. The invention comprises automatically subjecting each container to be inspected to a predetermined force so as to cause each container to emit a click as a result of relative displacement of the container and its liquid contents and determining whether the container has adequate vacuum by measuring the time interval between application of the predetermined force and the occurrence of the click.
In yet another system for checking seal integrity, U.S Pat. No. 2,689,647 Hofstetter et al, BOTTLE CAP POSITION DETECTOR, a device for detecting and rejecting containers having screw caps containing sealing liners which engage against the mouth rims of the bottles is provided. In the machine application of the caps to the bottles, an occasional cap may have been misapplied to the bottle for any of various reasons including misalignment of the cap and bottle threads resulting in a "cocked" position of the cap on the bottle, as well as accidental exclusion of the liner from the cap or the inclusion of more than the proper single liner. In Hofstetter, the detector is an assembly comprising a holder, a movable detector finger, and a switch actuated by the movable detector finger to reject faultily capped bottles. The holder is adapted to ride upon the bottle flange as the bottles are advanced beneath and past the detector finger. The assembly is adjustable to a predetermined spacing so that bottles lacking liners or, where the cap has been screwed in a cocked position, the finger will detect the improperly sealed bottle and through an appropriate switch actuate a mechanism for rejection of the bottle. A normally and properly applied cap will deflect the finger to only a limited degree and to which the switch control is unresponsive in its rejecting function.
Another invention, U.S. Pat. No. 3,469,689, O'Neill, IMPROPERLY SEALED-CONTAINER REJECTOR, describes an apparatus for electronically detecting and rejecting improperly sealed containers utilizing a proximity detector which controls the frequency of an oscillator in response to the distance between the detectors and containers' top sealed under vacuum. The process of sealing under vacuum causes container lids to flex inwardly under atmospheric pressure. If for some reason the container is not properly sealed, the cap will not deflect the intended degree. Thus the degree of deflection of the cap or container end can be relied on to separate the improperly sealed containers from the properly sealed containers. In this invention a plastic mounting sled or skid is supported by a flat spring or resilient member along the longitudinal path of movement of the jars. The sled is normally supported at a predetermined height so that proximity sensor housed within the plastic sled can detect the requisite degree of deflection of the top surface of the jar lid. This arrangement makes it essential that the measurement be taken at a corresponding center location on the jar lid for each successive jar. To insure reading at this center position, a side probe is provided housing a second proximity sensor. These sensors work in conjunction with an air nozzle which is activated to knock the jar off the side of the conveyor when an improperly sealed jar passes the sensor.
The foregoing inventions pertain only to vacuum packed containers, whereas the present invention can be applied to either vacuum or non-vacuum packed containers and differs in the means for determining a properly or improperly sealed container. Also in the foregoing inventions, the means of detecting properly or improperly sealed containers rely on displacement measurements of the containers metallic or rigid top whereas the present invention relies on measuring the applied seal force on a resilient container top and comparing the applied seal force to a predetermined idealized standard. In the present invention, the sensing means is provided by a force transducer integral with the container sealing apparatus and responds to the force exerted on the sealing means during the sealing process. The response to the force is then electronically compared in near real time to predetermined force values taken on an ideally sealed assembly of an identical container. Containers which are improperly sealed will exhibit force values which deviate from the standard and will be automatically ejected, inprocess, from the conveyor.
Accordingly, it is an object of this invention to provide a unique and improved apparatus, system and method for electronically detecting, in-process, properly and improperly sealed containers and for ejecting improperly sealed containers.
Another object of the present invention is to provide an apparatus, system, and method capable of high-speed, uninterrupted operation for one hundred percent seal integrity inspection.
Another object of the present invention is to provide a force measuring transducer integral with the pressure block or integral with the sealing cam.
Another object of the present invention is to provide a means for sampling the force applied to the cap as it is being applied.
Another object of the present invention is to provide a means of comparing the force values against pre-determined standard force values.
Another object of the present invention is to provide a means for automatic rejection of improperly sealed containers.
Another object of the present invention is to detect and arrange for the rejection of containers with gross and/or marginal defects.
Another object of the present invention is to provide displays of the number of good and defective containers.
Another object of the present invention is to provide a display showing production rate.
Another object of the present invention is to provide outputs of all operating parameters and information and to perform statistical evaluations.
Another object of the present invention is to provide outputs for closing down the capper if a pre-selected, programmable number of consecutive rejects are detected.